Definition

Moyamoya is the Japanese word for “puff of smoke”, which is how the tangled blood vessels caused by the blocked arteries at the base of the brain appear on angiography. Moyamoya disease is a rare, progressive cerebrovascular disorder that generally affects children, although it can affect adults.

Causes

While the precise causes of moyamoya are unknown, there appears to be some genetic component, as it is seen to run in families. Patients with Down syndrome, neurofibromatosis, sickle cell anemia and a history of radiation to the brain may develop acquired moyamoya malformations.

Risk Factors

Risk factors associated with an increased chance of developing moyamoya include:

  • Japanese heritage
  • Female gender
  • Family history of moyamoya
  • Age (more common in children)
  • Down syndrome
  • Sickle cell anemia and other hematologic disorders
  • Various congenital syndromes
  • Radiation exposure

Symptoms

Children and adults often present differently. Children tend to have symptoms such as paralysis, sensory dysfunction, involuntary movement, headaches, dizziness and seizures. Adults may experience similar symptoms but more frequently have sudden onset of bleeding in the brain.

Diagnosis

  • Magnetic resonance angiography (MRA)
  • Cerebral angiography is the gold standard

Treatment

Once blockage of the blood vessels begins, the condition tends to resist medical management. There are several surgical options, all of which aim to increase blood flow to the brain:

  • Direct superficial temporal artery to middle cerebral artery bypass is considered the treatment of choice. This is also called an external carotid-internal carotid bypass.
  • Multiple small burr holes placed in the skull to allow for growth of new blood vessels from the scalp.
  • Encephaloduroarteriosynangiosis (EDAS) - a scalp artery is dissected over a course of several inches and then a small temporary opening is made in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
  • Encephalomyosynangiosis (EMS) - the temporalis muscle is dissected and through an opening in the skull, placed onto the surface of the brain.

Prevention

There is no known way to prevent the development of moyamoya disease. Management with a skilled stroke neurologist early in the course of the disease is important in avoiding major strokes and their associated morbidity.

Disclaimer

Content generated and provided by Joshua B. Bederson, MD, Professor and Chairman of the Department of Neurosurgery at The Mount Sinai Health System. Some of the information contained in this article was adapted from the National Institutes of Health. Last reviewed June 2011 by the Department of Neurosurgery at The Mount Sinai Health System.

If you want to learn more about moyamoya disease call the Mount Sinai Department of Neurosurgery at 212-241-2377.